Assessing the effects of post‐pine beetle forest litter on snow albedo

The effect of forest litter on snow surface albedo has been subject to limited study, mainly in the hardwood‐dominated forests of the northeastern United States. Given the recent pine beetle infestation in Western North America and associated increases in litter production, this study examines the effects of forest litter on snow surface albedo in the coniferous forests of south‐central British Columbia. Measured changes in canopy transmittance provide an indication of canopy loss or total litterfall over the winter of 2007–2008. Relationships between percent litter cover, an index of albedo, snow depth, and snow ablation during the 2008 melt season are compared between a mature, young, and clearcut coniferous stand. Results indicate a strong feedback effect between canopy loss and subsequent enhanced shortwave transmittance, and litter accumulation on the snow surface from that canopy loss. However, this relationship is confounded by other variables concurrently affecting albedo. While results suggest that a relatively small percent litter cover can have a significant effect on albedo and ablation, further research is underway to extract the litter signal from that of other factors affecting albedo, particularly snow depth. Copyright © 2010 John Wiley & Sons, Ltd.     

Internal catchment process simulation in a snow‐dominated basin: performance evaluation with spatiotemporally variable runoff generation and groundwater dynamics

Hydrologic models have increasingly been used in forest hydrology to overcome the limitations of paired watershed experiments, where vegetative recovery and natural variability obscure the inferences and conclusions that can be drawn from such studies. Models are also plagued by uncertainty, however, and parameter equifinality is a common concern. Physically‐based, spatially‐distributed hydrologic models must therefore be tested with high‐quality experimental data describing a multitude of concurrent internal catchment processes under a range of hydrologic regimes. This study takes a novel approach by not only examining the ability of a pre‐calibrated model to realistically simulate watershed outlet flows over a four year period, but a multitude of spatially‐extensive, internal catchment process observations not previously evaluated, including: continuous groundwater dynamics, instantaneous stream and road network flows, and accumulation and melt period spatial snow distributions. Many hydrologic model evaluations are only on the comparison of predicted and observed discharge at a catchment outlet and remain in the ‘infant stage’ in terms of model testing. This study, on the other hand, tests the internal spatial predictions of a distributed model with a range of field observations over a wide range of hydroclimatic conditions. Nash‐Sutcliffe model efficiency was improved over prior evaluations due to continuing efforts in improving the quality of meteorological data collection. Road and stream network flows were generally well simulated for a range of hydrologic conditions, and snowpack spatial distributions were well simulated for one of two years examined. The spatial variability of groundwater dynamics was effectively simulated, except at locations where strong stream–groundwater interactions exist. Model simulations overall were quite successful in realistically simulating the spatiotemporal variability of internal catchment processes in the watershed, but the premature onset of simulated snowmelt for one of the simulation years has prompted further work in model development. Copyright © 2011 John Wiley & Sons, Ltd.     

Cloud water interception in the high altitude tree heath forest (Erica arborea L.) of Paul da Serra Massif (Madeira,Portugal)

Cloud water interception (CWI) occurs when cloud droplets are blown against the forest canopy, where they are retained on the vegetation surface, forming larger water droplets that drip into the forest floor. CWI was measured from 1 October 1997 to 30 September 1999, on a first‐line tree heath (Erica arborea), at Bica da Cana, Madeira Island. Rainfall was corrected for wind‐loss effect and compared with throughfall and other climatological normals. The CWI depletion rate along a forest stand transect was also analysed during three distinct fog events in 2008. Cloud water was 28 mm day^?1, corresponding to 68% of total throughfall and 190% of the gross precipitation. Cloud water correlates directly with monthly normals of fog days and wind speed and correlates inversely with the monthly air temperature normal. CWI has an exponential correlation with monthly relative humidity normal. Cloud water capture depletion along the stand shows a logarithmic decrease. Although a forest stand does not directly relate to a first‐line tree heath, this study shows that CWI is a frequent phenomenon in the Paul da Serra massif. Restoration and protection of high altitude ecosystems in Madeira should be a priority, not only for biodiversity, ecological and economical purposes but also for its role in regional water resources. Copyright © 2011 John Wiley & Sons, Ltd.     

Integrated Electrical Resistivity Tomography and Ground Penetrating Radar Measurements Applied to Tomb Detection

The integrated use of electrical resistivity tomography (ERT) and ground penetrating radar (GPR) measurements, and in particular the joint analysis of 2D and 3D data, can represent a valid solution for target identification at complex archaeological sites. A good example, in this respect, is given by the case study of a Phoenician–Punic necropolis in the archaeological site of Nora, in southern Sardinia (Italy), where GPR and ERT measurements were collected before site excavation. In this specific case, the mix of soil and air in the buried chambers, as well as the orientation and the complex spatial distribution of these structures into the sandstone bedrock, generated a number of anomalies difficult to interpret only using 2D results. Only the integration of all GPR and ERT data in a 3D view, and the comparison with archaeological evidence after the excavation, allowed a solid interpretation of geophysical anomalies visible in the 2D sections. Overall, this case study demonstrates the efficiency of the combined use of GPR and ERT acquisitions and shows how, in general, only the joint analysis of 2D data and in a 3D view can help the interpretation of the real distribution of the buried archaeological remains at similar archaeological complex sites.     

Analysis of occurrence patterns and biological factors of cetaceans based on long‐term and fine‐scale data from platforms of opportunity: Madeira Island as a case study

Management and conservation issues are addressed through the identification of areas of particular importance, which requires the acquisition of baseline information on species distribution and dynamics. These types of data are particularly difficult to obtain at high resolution for large marine vertebrates like cetaceans, given that dedicated surveys are complex and logistically expensive. This study uses daily presence–absence sighting data of cetaceans collected year‐round from whale‐watching boats to support the theory that fine‐scale data obtained from platforms of opportunity can provide valuable information on species occurrence and group dynamics. Data from 7,551 (daily) sightings comprising 22 species were collected from 3,527 surveyed days over 11 years (mean of 321 days per year, SD = 17) in the pelagic environment of Madeira Island. Cetaceans were observed on 92% of the surveyed days, and a mean of 15.4 (SD = 1.5), 8.2 (SD = 2.0) and 2.1 (SD = 1.2) species were recorded per year, month, and day, respectively. There were significant differences in the number of species per month (p < .001), with the highest diversity recorded in June. At least nine species, comprising 96% of all sightings, were found to use the Madeiran waters on a regular basis, such as the Atlantic spotted dolphin (Stenella frontalis), the short‐beaked common dolphin (Delphinus delphis), the bottlenose dolphin (Tursiops truncatus), and others featured in the Red List of the International Union for Conservation of Nature as Endangered, Vulnerable, and Data Deficient. In addition, 10 species were found to use the Madeiran waters for travelling, feeding, resting, socializing and calving, which suggests that the southern and southeastern waters of Madeira Island constitute an area of interest for cetaceans. This study characterizes the cetaceans’ community structure (occurrence, aggregation sizes, behaviours, proportion of calves, and inter‐specific relationships) of a poorly studied region, providing important information for managers. Finally, the advantages and limitations of using fine‐scale data from a type of platform of opportunity that is increasing along coastlines globally are discussed.     

Fracture system in Phlegraean Fields (Naples,southern Italy)

During the 1983 seismic crisis in the Phlegraean Fields bradyseismic region (southern Italy), a structural analysis of the area was carried out.With a detailed field survey based on a net of 34 measure stations, a total of 536 fractures (mainly joints and a few normal faults) were measured on a 10 × 10 km area in volcanites capable of memorizing post depositional stress activity by fracturing.The analysis of the collected data was performed with the data bank of the University of Rome computer facilities. The azimuthal analysis of total fractures showed a nonrandom distribution with 5 major sets: N13°E, N45°E, N14°W, N55°W and E-W. These preferential orientations have been detected with an automatic fitting of gaussian curves (bell curves) on the azimuthal histograms. The areal distribution showed that all these fracture sets are in general present in the main collapse area. An azimuthal analysis performed by selecting the data collected for rocks older than 4,600 y BP showed a possible youngest age for the N14°W set (domain) (E-W extension). Fractures with an «opening» wider than 1 cm presented the same 5 azimuthal sets and fit fairly well with a concentric distribution around the main collapse area. The presence of an analogous radial pattern is not evident. A tentative interpretation model relates the superficial fracture sets to two possible causes: volcanic activity, including doming and collapsing, and propagation of active tensile deformations in the sedimentary basement due to regional stress trajectories.Contribution of «Centro di Studio per la Geologia dell'Italia Centrale», CNR, Roma.     

Mafic inclusions in the silica-rich rocks of the Tolfa-Ceriti-Manziana volcanic district (Tuscan Province,Central Italy): Chemistry and mineralogy

Summary A chemical and mineralogical study of magmatic inclusions in the silica-rich rocks of the Tolfa-Ceriti-Manziana sector (Tuscan Province, Central Italy) shows that they can be grouped according to their degree of alkalinity. We distinguish: TCM latites (TCML) with an alkaline-potassic affinity; Ceriti latites (CL) with calc-alkaline affinity; and Manziana shoshonites and latites (MS-ML) with an affinity intermediate between alkaline and subalkaline. The latter are hybrid rocks originating from the mixing of two magmas with slightly different geochemical affinities.These magmas may represent liquids derived by partial melting of a heterogeneous mantle, metasomatized by a crustal source. The most alkaline magmas (TCML) are associated with the largest degree of metasomatism which, if more pronounced, could lead to the production of the potassic magmas of the Roman Province.

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Mafische Einschlüsse in den Si-reichen Gesteinen des vulkanischen Distriktes von Tolfa-Ceriti-Manziana (Toskanische Provinz, Zentralitalien): chemie und mineralogie

Zusammenfassung Eine chemische und mineralogische Untersuchung der magmatischen Einschlüsse in den sauren Gesteinen des Tolfa-Ceriti-Manziana Sektors (Toskanische Provinz, Zentralitalien) zeigt, daß sie nach dem Grad der Alkalinitdt unterteilt werden können. Wir unterscheiden TCM latite (TCML) mit einer Alkali-Kalium Affinität; Ceriti Latite (CL) mit einer kalkalkalischen Affinität und Manziana Shoshonite und Latite (MS-ML) mit einer Affinität die zwischen alkalisch und subalkalisch liegt. Die Letztgenannten sind Mischgesteine, die durch die Mischung zweier Magmen mit verschiedenen geochemischen Affinitäten entstanden sind.Diese Magmen, die genetisch nicht mit den Wirtsgesteinen in Beziehung stehen, dürften Schmelzen repräsentieren, die auf teilweise Aufschmelzung eines heterogenen Mantels, der durch eine krustale Quelle metasomatisiert wurde, zurückgehen. Die am meisten alkalischen Magmen (TCML) sind mit dem höchsten Grad der Metasomatose assoziiert, der wiederum, wenn noch stärker entwickelt, zur Entstehung der kalireichen Magmen der römischen Provinz führen könnte.

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With 9 Figures     

Observed heating effects of conjugate photoelectrons

A gridded spherical electrostatic analyzer aboard Injun 5 has been used to measure fluxes of thermal and hyperthermal electrons at subauroral latitudes in the midnight sector of the northern ionosphere between altitudes of 2500 and 850 km. Due to the offset between the geomagnetic and geographic poles hyperthermal fluxes, consisting of energetic photoelectrons that have escaped from the sunlit southern hemisphere are observed along orbits over the Atlantic Ocean and North America but not over Asia. The ambient electron temperatures (T_e) near 2500 km have their highest values at trough latitudes for all longitudes. At altitudes near 1000 km elevated electron temperatures in the trough were not a consistent feature of the data. Equatorward of the trough, in the longitude sector to which conjugate photoelectrons have access, T_e ～ 4000 K at 2500 km and ～ 3000 K at 1000 km. For regions with the conjugate point in darkness T_e ? 2300 K over the 1000–2500 km altitude range. The effective thermal characteristics of conjugate photoelectrons are studied as functions of altitude and latitude. The observations indicate that (1) at trough latitudes elevated electron temperatures in the topside ionosphere are mostly produced by sources other than conjugate photoelectrons, and (2) at subtrough latitudes, in the Alantic Ocean-North American longitude sector, conjugate photoelectrons contribute significantly to the heating of topside electrons. Much of the conjugate photoelectron energy is deposited at altitudes >2500 km then conducted along magnetic field lines into the ionosphere.